Continuously extensible, retractable, and collapsible structure



LARSON CONTINUOUSLY EXTENSIBLE Feb. 8, 1949. K. o.

AND COLLARSIBLE STRUCTURE FiledJan. 2, 1,247

IMQ/M024 Kara! 0, La/i022 ,y /2

Feb. 8,y 1949, K. o. LARsoN CONTINUOUSLY EXTENSIBLE 'RETRACTABLE,

AND COLLAPSIBLE STRUCTURE 4 Sheets-Sheet 2 Filed Jan. 2, 1947 Fell 8, 1949. K. o. LARsoN `comINUousmf EXTENSIBLE, RETRACTABLE ARD COLLAPSIBLE STRUCTURE 4 Sheets-Sheb 3 Filed Jail. 2, 194'? E@ .5 /Z /3 27 Z5 Feb. 8, 1949. K, o; LARSON 2,461,429 l CONTINUOUSLY EXTENSIBLE, RETRACTABLE,

AND coLLAPsILEA STRUCTURE F'led Jan. 2, 1.947 I 4.1Sheets-Sheet 4 Patented Feb. 8, 1949 UNITED STATES PATENT OFFICE CONTINUOUSLY EXTENSIBLE, RETRACT- ABLE, AND COLLAPSIBLE STRUCTURE Generally stated, my present invention relates to elongated structures that are readily convertible from conditions of rigidity to conditions of collapslbility. The invention is adapted to a wide range of applications including extension ladders for use by firemen and the like to reach the upper stories and roofs of buildings, emergency extension bridges (mainly foot bridges) for use in various kinds of rescue work, extensible and retractabie cranes or supporting arms, and extenl0 sible and retractable troughs or channels for conveyance of various materials and products of commerce.

More specifically stated, my present invention relates to collapsible structures of the above analogous types and kinds which are made up of longitudinally aligned sections permanently joined together, that is, permanently joined to the extent that the joints need not be( disassembled for purpose of conversion of the structures from conditions of rigidity to conditions of collapsibility.

In practicing the invention according to the preferred-example illustrated, jointed, elongated` structures of the kinds described and other analogous kinds may be made in Widely-varying overall lengths and the longitudinally-extended sections thereof are progressively convertible from conditions of collapsibility to conditions of rigidity and vice versa, so that the structure may be 3 stored and transported in a minimum of space and may be progressively projected from the place of storage in a condition of rigidity.

An object of the present invention is the provision of an elongated unitary structure which is readily convertible from a condition of rigidity to a condition of collapsibility. Y

Another and more specic object oi the invention is the provision of a unitary structure of the kind described made up of a plurality of joined tions thereof may be'progressively converted from 50 conditions 'of Acollapsibility to conditions of rigidity.

A still more specific object of the invention is the vprmfision of 'an elongated structure having with mechanism for continuously-projecting and retracting the structure, said mechanism involving means for continuously converting the sections oi the structure from conditions of collapsibility to conditions of rigidity under extending movements of the structure and for progressively converting the structure sections from conditions of rigidity to conditions of collapsibility or nonrigidity under retracting movements of the structure. In the preferred embodiment of the invention illustrated, the several sections of the structure are provided with latch mechanism for independently releasably locking the sections in conditions of rigidity, and means are provided for progressively acting upon these latch mechanisms under projecting movements to set the latches in locked position and are progressively operative on the latch mechanism on retracting movements thereof to set the latches in inoperative or unlocked positions. Y.

The above and other highly important objects and advantages of the invention will be made apparent from the following speciiication, claims and appended drawings.

Fig. 1 is a perspective view of an extension ladder and ladder-receiving' supporting, and dispensing structure constructed in accordance with the invention;

Fig. 2 is an enlarged longitudinal sectional View taken on the line 2 2 of Fig. 1;

Fig. 3 is a fragmentary plan View taken on the line 3 3 of Fig. 2;Y

Fig. 4 is a transverse sectional view, on a still further enlarged scale, taken on the line 4 4 of Fig. 1;

Fig. 5 is a transverse sectional view taken on the line 5 5 of Fig. 1 and on a somewhat enlarged scale;

Fig. 6 is a fragmentary sectional'view taken on the line 6 6 of Fig. 4;

Fig. 7 is a View in elevation of the free or eX- tended end ofthe extension ladder structure of Fig. 1;

Fig. 8 is a still further enlarged fragmentary detail View, in side elevation and with some parts broken away, of the extension ladder structure of previous figures;

Fig. 9 is a detail sectional view taken on the line 9 9 of Fig. 8; j

Fig. 10 is a view similar to Fig. 9 but showing the hand rail and associated parts tipped to their inoperative or collapsing positions;

Fig. llris a fragmentary sectional view on an enlarged scale taken onthe line H il of Fig. 5;-

the';characteristics4 last above 'defined together 55 y Fig. 12 isa longitudinal sectional viewV taken 3 on the line iZ-IZ of Fig. 13 and illustrating a somewhat modified form of the invention;

Fig. 13 is a transverse sectional View taken on the line i3-i3 of Fig. 12;

Fig. 14 is a detail sectional view taken on the line id-ili of Fig. 8;

Fig. 15 is a fragmentary longitudinal sectional View taken on the line I5-l5 of Fig. 16 showing a modified 'formof supporting, guiding 'and converting Imeans for ladder and other extensible and contractible devices of the invention; and

Fig. 16 is a detail sectional view taken on the line IS-I of Fig. 15.

(Description-Figs. 1 to -`1-i yinclusive) In Figs. l to 11, inclusive, the invention -is shown as embodied in an extension ladder structure and one form of handling mechanism therefor is illustrated. The extension ladder of these figures comprises laterally-spaced parallel rails l, vwhich Vmayhereinafter be singularly or jointly referred Vto as main members, and laterallyspaced paralleltruss members 2, which, in the present instance, serve also as hand rails. The ladder rails or'members I 'each'comprise a longitudinally-extended Aseries of sections 3, which sections are yconnected together by hinge joints for movements on axes extending transversely of the structure. Theaxes of hinge joints of each ladder rail ormain member 'are aligned with the axes of the joints between sections lof the opposite' ladder-rail. The 'hinge joints between longitudinally-adjacent ladder r'ail sections are .best vshown in Figs. 6 and 8 and involve hinge pins gli. spacedrladder rails or main members i are rigidly connected by ladder rungs 5, which, as will hereinafter-be seen, form the bottom 4of a channellike structure when "the: parts are operativeli7 positioned.

The hand-.wail acting portions of the truss members 2 are each made up of seriesof sections 6 (preferably tubular sections). Longitudinally adjacent sections 6 are .connectedby universal 'Laterally-opposite sections 3 of the hinge jointsf'i yallowing limited swivelling and universal swinginggmovements between adjacent sectionS'B.

A preferred form of these hinge joints'fg'is shown best in Figs.` 8 'and 14, and Veach said. joint is comprised as follows: one rend of each tubular f section 6 is provided with. a bifurcated head telescopically applied therein inthe manner oa plug and `welded or otherwise irigidly Asecured thereto as best shown in Fig. 14. The opposed inner surfaces of the spaced flanges of these bifurcated joint heads 8 are flat, and parallel to one another and the outer surfaces'thereof are cross-sectionally segmental. Pivoted and axially slidable Within each bifurcated head vis'aballacting ring 9 having fiat surfaces spaced from the opposed inner'surfaces of the bifurcated head S v,and havingl a spherical-peripheral surface intermediate its flat ends. Preferably, and as shown, the ball-acting elements 9 aremounted in the bifurcated heads '8, for pivotal Aand axial sliding movementsfon Vpivot lpins i@ extending therethrough and the opposite flanges of the bifurcated heads 8 and press rit inthe latter. The pivot or hinge pins is (see particularly Fig. '8)`are rcoaxially-aligned `with the fiat opposed surfaces of the rings 9, and the axis of each of these pins is located in a plane extending transversely of the extendedstructure-andintersecting the axis of the hinge pin 4 of an-adjacent hingefjoint betweenadiecent ladder rail-forminszmain inember sections. It may also be said that the axes of the pins IB extend in the direction of the depth of the truss members 2. The ball-acting rings 3 (see particularly Fig. 14) are seated in mating spherical sockets formed in tongues of joint heads Il telescopically applied in and welded or otherwise rigidly secured to adjacent ends of longitudinally-adjacent tubular truss memberise'etions. Inconnection with the joints i, itis 'important to notethat the head elements il are spaced from the opposite flanges of the -head elements 8 to allow limited sWivelling and universal swinging movements between adjacent `sections 6 of members 2, in addition to relative end Vportions of these struts i 2 are diametrically reduced to .provide pivot lpin-acting Shanks i4. These `pivot pin-acting rshanlrs `|-4 `are preferably solid and, as shown,l are provided `with yenlarged heads telescopically applied in the tubular VAportionsof the struts i2 and .permanently secured thereto'by'welding, bracing 0 1' the like.

rhe universal hingejoints Beach comprise the pivot pin-acting Shanks `I4 of the struts 12, a body l5 in which the pivotpin-acting `shanks i'of the struts are pivoted, and opposed'bearing lflanges Iii .rigidly lcarried by the ladder -railforming main member sections 3 and in which the said bodies i5 are pivoted. In the preferred arrangement illustrated, the bodies lfare in the nature of pivotpins extending between and having their'opposite ends pivoted in opposite cooperating fianges i6 onaxes extendingparallel tothe longitudinal'directions of theirrespective cooperating mainmember sections 3. By'referenceparticularly torFig. 8, it -will alsoibe 'seen that, in the 'preferred embodiment illustrated, the axes of the'pivotipin-acting Shanks VHl intersect Vand are perpendicular tothe-axes ofthe bodies i5. The 1 compound hinge joints i3 are located intermediate adjacent hinge pins' on pivots 4 of the ladder rail-,acting main 'sectioned With the arrangement idescribed, it will be clear that the centers H-"of universal movements of the truss member section joints 'Larelocated inand arezmovable in planes intersecting the axes (hinge pins A) kof adjacent xladder'rail-forming Ina-in -membersections 3. Bycomparison with-Figs. 9 .and10,for 4exarnplefit"will be 'seen that the-truss memb'ersf'Z e-aremova'ble on the axes of bodies i5 -from foperativetruss-acting positions shown in Fig. 9, wherein the centersoi movement I'I of the truss member 'section joints 1 are angularly dispbsed'ipreferably perpendicularly disposed) withrespect tofthefaxes ofthe hinge Vjointsipinsli) 'of the ladder railracting main memberfsections 3 (seefFig. i9), `to inoperative .structure-collapsing A`positions, Vwherein the centers ll of universal swinging movements `of truss memberjoints'l :are alignedwith hinge axes 'ofthe main memberwsecti'ons '3 (pinsf). "From anzexaminationof-the'drawings, it should-beclear that the structure will be relatively very rigid when the parts are operatively positioned as in Fig. 9, but will be readily collapsible when the parts are inoperatively positioned as in Fig. 10.

For the purpose of independently and releasably locking the sections 6 of truss member 2 in their operative truss-forming positions, I provide independent latch mechanisms for each and every such section. In the preferred embodiment of the invention illustrated, these latch meohanisms each comprise the reduced diameter shank portion I4 of a truss member strut I2, a latch detent I6 in th-e nature of pins passed diametrically through and projecting outwardly of the inner end portion of a pivoted shank. I4, and cooperating latch detent-receiving notches .I9 in the inner peripheral portions of circular bosses formed on the opposed faces of cooperating pairs of flanges IS (see particularly Figs. 8, 9 and 10). Portions of flanges I6 forming opposite walls of the notches I9 serve as opposed latch lugs or shoulders. The shank-acting portions M of the struts I2 are axially, slidably and pivotally mounted in the bodies I5 and are yieldingly biased outwardly towards their latclied locked positions shown in Figs, 8 and 9 by coil compression springs that are compressed between anges 2i fast on the struts 2 and bearing washers 22 slidably mounted on the shank'portions le of the struts I2 and bearing against the circular peripheral portions of the flanges I6. Hence, it is important to note that the latch mechanism just described not only locks the sections 5 of truss member 2 against lateral swinging movements on the axes of bodies I5, but pivotal movements on the axes of the strut shanks also positively locks the said sections against I4. Hence, when the parts are in their operative positions of Figs. 8 and 9, the structure will be comparatively very rigid. From the drawings, it should also be apparent that when the parts are moved to their operative positions of Figs. 8 and 9, the latch mechanisms described will automatically lock, under the actions of springs 2D, and that unlocking of the latches can only be accomplished by moving the shank portionsIlI of the struts i2 inwardly, against the actions of springs 20, through the bodies I5 suii'iciently to release the opposite ends of pins I8 from the notches i9. 1n this connection, it is important to note that the joints 'I' allow, in addition to swivelling and universal swinging movements described, limited movements of each truss section 6 in respect to adjacent sections in a direction axially of the pins l!) of joints l, and shanks I4 of joints I3, and this to the extent of the clearances between the joint elements 9 and il and the adjacent iianges of bifurcated heads 8, these last-described axial movements being particularly important in the locking and releasing latches of selected sections independently of others. if desired, sufcient clearance could be providedrbetween the cooperating coupling or joint heads Zi and 9 of the universal joints l to permit locking and releasing of the latch mechanism of any truss section independently of any others thereof without requiring movement of any other truss section axially of its shank, but in the preferred embodiment of the invention, illustrated, the

clearance between cooperating joint heads 8 and 9 is somewhat less than the depths cf the latch notches I9, so that complete releasing or unlocking of any one latch can be accomplished only by Ataking up the clearances between cooperating heads 8 and 9 of a plurality of adjacentjoints 1 (2, .3 or more, for eample). However, attention is also called to the fact that special clearances between the heads 8 and 9 of joints 'I of the kind described, and for the purpose of facilitating the locking and unlocking function of the latches, may be dispensed with in favor of utilization of the normal working tolerances in the joints 'I and i3 for accomplishing the progressive locking and unlocking of the latch mechanisms. 'It-Will be understood, however, that in the latter instance, locking and unlocking functions of any particular latch will make use of the accumulated tolerances in a greater number of adjacent joints 6 and I3.

The handling and supportingmeans for the elongated jointed ladder structure illustrated may vary greatly in' design.Y However, the form of supporting and handling means for the jointed ladder structure illustrated in connection with Figs. l to ll, inclusive, and 14 embodies such features and characteristics as are necessary to accomplish the'desired result. This supporting and handling .mean of Figs. l to il, inclusive, (mainly Figs. l, 2, 3, 4, 5, 6, and l1) comprise a rectangular mounting frame 23 adapted to be mounted in an apertured support such as a platform,V and a drum-like container 25 mounted in the rectangular frame 23 through means including a combination bearing and gear box 26 adjacent one end of the drum and a bearing bracket 26 adjacent the other end of the drum. The drum-like container 25 is provided with a tangential outlet passage 2l shown best in Figs. l, 2 and 5. The radially-outer or upper wall of this tangential passage 21 is indicated by 28, and the radially inner or bottom wall thereof by 29, The said passage 2l is substantially the full width of the drum 25 and said drum and passage are of sucient width to receive the ladder structure when the hand rail providing truss members thereof are swung out laterally to their inoperative collapsing positions. Extending upwardly and outwardly from the drum passage 2 and forming integrally or rigid continuations thereof are like laterallyspaced tortuous channels 3D, each receiving a pluraiity of sections 3 of an opposite ladder railextended open slot to permit passage of the ladder rungs 5 therethrough.

By reference to Figs. l, 2, and 3 it will be seen that the bottoms 32 of the channels 3over which the bottoms of the sections 3 of main members I travel, are upwardly and outwardly vcurved from points of tangency with the common passage 21 to points thereonspaced somewhat from the free ends thereof and beyond which latter points the said bottoms 32 of the channels 30 are straight. In theory, the bottoms of the channels could be curved all the way to their ends, but in practice said channel bottoms will usually be made straight adjacent their free ends for distance equal to the length of several sections 3 and 6, the Yactual distance that the said channel bottomsaremade straight being determined largely by the degree of rigidity of support demanded for the extended structure and the space in any particular structure required to accomplish the locking and unlocking functions of the lat-ch mechanisms. `By reference particularly to Figs. l, 2 and 3, it will be seen that the spacedside walls der structure will be Wound upon the reel 34, `as best shown in Figs. 2 and 4, except for those portions thereof contained within theA channels 3B. When it is desired to extend the collapsed ladder structure, the pinions 38 are driven inv a clockwise direction in respect to Fig. 2. As thepinions 38 are rotated in a clockwise direction in respect to Fig. 2, the main member sections 3 and the truss member sections 6 will progressively move outwardly through the channels 36 and during such movement the sections 6 of truss members 2 will be progressively swung from their laterally outwardly-extended inoperative collapsing positions to their upstanding operative truss-forming positions, under the influence of the cam-acting rollers 33. In this respect, it will be understood that the channels 36 are provided with rollers 33 at equally-spaced points throughout their lengths and that the several rollers 33 of each series thereof are so orientated each in respect to the others thereof that the centers of universal swinging or pivotal movements I? of the joints 'l of each truss member 2, during their passage through a channel 30 define spaced points in a compound curve that is tangent at one end to a plane intersecting the centers of universal swinging movements of a plurality of operativelypositioned joints l and its other end is tangent to a plane intersecting the axes of universal swinging movements of a plurality of inoperativelypositioned joints 1. Of course it Will be understood thatI the truss members will automatically be locked in their operative positions before being discharged from the channels Se by engagement of the latch pins i8 in their cooperating notches i3. The structure described will be comparatively very rigid and strong when properly engineered and built of first-class materials, and may be made in various lengths up to 200 feet or more. Retraction of the extended structure and winding thereof upon the reel 3-3 is, of course, accomplished by releasing the pawls 63 and then rotating the reel 34 in a counter-cloclnyise` direction with respect to Fig. 2, through the mechanism described or otherwise.

While the structure of Figs. 1 to 11, inclusive, and 14 was primarily designed for use as extension ladder structure and has been described as such, it will be understood that the structure of these figures is adaptable for numerous other uses, such, for example, as booms, cranes, supporting arms, and other analogous uses all without modication, and that the said structure of Figs. 1 to 11, inclusive, and 14 may be adapted, by slight modification Within the spirit of the invention, to numerous other uses, some of which are exemplified in Figs. 12 and 13. In Figs. 12 and 13, I have shown the generally channelshaped skeleton structure of Figs. 1 to 11, inclusive, and 14 equipped with sectional channel bottom-forming plates le and sectional channel sideforming plates 45. Except for the addition of the sectional plates 44 and 45 in Figs. i2 and 13,

the structures of these gures may be assumed to be identical to the structure of Figs. l to 11, inclusive and 14, and to operate and function in exactly the same manner. By reference particularly to Fig. 12, it will be seen that the channel bottom-forming plate 44 is made up of an aligned series of plate sections 416 reach approximately equal to the length of a main member section 3 and that the channel side-forming plates 45 are each made up of a plurality of aligned plates 4'! each equal in length to an associated main member section 3 and truss memberk section 6. The

sections Alt andjadjacent side-forming sectionsv d? are closely spaced as shown best in Fig. 12 and, of course, it is desirable that the said spaces be aligned With the axes of the joints between main member sections 3.

The .modiedstructurefof Figs. l2 and -13 is obviously very desirable for use as an extension bridge, for example,'and for use as an extensible and retractable trough, channel or chute, for conveyance of -various materials and products of commerce.

' (Description of Figs. 15 and 16) In Figs. 15 and 16, I have shown a somewhat modied arrangement for supporting the extended structure and for progressively converting the same from a condition o f collapsibility to a condition of rigidity and vice versa under longitudinal movements thereof.v In-,these gures, the extensible and retractable ladder structure is identical to the ladder structure shown in Figs. 1 to 11, inclusive, and 14, as are also the camacting guide rollers for moving the truss members of the ladder structure between operative and inoperative positions, and all parts in these :figures identical to parts of Figs. 1 to 11, inclusive, and 14 are indicated by like characters. In these Figs. 15 and 16, however, the-channels 3U of theV previously-described ligure Whose function is largely that of supporting the rollers 33 and supporting and guiding the sections 3 of the main members I,

' have been omitted in favor of a skeleton framework 48 and main member guide rollers 4S. The skeleton framework 48 may take various different forms' but, as illustrated, comprises laterallyspaced,` parallel, longitudinally-directed beams 50 extending from and anchored to a suitable supporting structure, such as the drum 25, for example, and which beams 50 may be assumed to curve outwardly and upwardly from the support much as do the bottomV portions or walls 32 of the channels v3l) of Figs. 1,V 2 and 3. The said skeleton framework further comprises a series of transversely-extending cross members 5I,A

strut-acting members 52, and curved longitudinal beams 53. The beams 54 are curved much as are the portions of the walls of the channels 36 immediately radially outwardly of the rollers 33 of Figs. 1 to 11. The rollers 33 of Figs. 15 and 16 are directly journalled in U-shaped brackets 55 that are bolted or otherwise rigidly secured to the beams 54 as at 56. In Figs. 15 and Y16, the series of rollers 33 for cach truss member 2 may be assumed to correspond in numbers, spacing, and orientation to the rollers 33 of Figs. 1 to 11, inclusive. Y

Probably the main advantage in the structure of Figs. 15 and 16 over that of the structure of Figs. 1 to 11, inclusive, and 14 is the use of the rollers 49 for supporting and guiding the main member sections 3 of the ladder structure, Whereby to reduce to a minimum frictional resistance to extending and retracting movements of the ladder or analogous jointed structure. By reference particularly to Fig. 16, it will be seen that the rack teeth 39 of the main member sections- 3 have Vbeen reduced in width andthe bottom laterally-spaced edges of said sections 3 have been rounded to conform to the concave 1 1 surfaces'of the rollers t9 of-'Figs 15 and 16 which serve both to carry the radial load imposed thereon and to guide the main member sections 3 against laterally-shifting movements. Preferably and as shown in-Fig. l5, each roller i9v is spaced directly under a roller-33,A but this may be varied Without departing fromv the spirit of the invention. In referring to Fig. l6,` it should be borne in mind that there are a spaced` series of so-called strut members 52 in the skeleton framework described and that these progressively change shape along that portion ci 'the' structure where the side-acting truss members are being moved from operative to inoperative positions.

What I claim is:

1. In an elongated structure of the-classy described, an elongated main member comprising a longitudinally-aligned. plurality of rigid sections hinged together for movements on axes extending transversely of the structure; an elongated truss member generally parallelY to the main member vand comprising a longitudinally-aligned pluralityv of 'rigid sections, adjacent trussfmember sections being connected by joints permitting limited swivellngand universal swinging movements therebetween, said truss-member sections being connected to adjacent main1 member sections by joints permitting limited'pvotal move'- ments on axes extending" longitudinally and transversely of the structure; the centersl'ofiuniversal swinging movements-of the joints between adjacent trussV member sections being-'locatedin and movable in planes extending transversely of the' structure and including the axes of joints between adjacent main member sections', the said joints between the' trussL member sections and main mem-ber sections allowing swinging movements of theftruss'member sectionsV from operative truss-forming positions to" inoperative" collapsing positions whereinthe centers ofuniversa-l movements between truss member'sections are aligned with hinge axes'ofmain member sections;

2. In an elongated Vstructure-of the class'v described; an elongated main member-comprising a longitudinally-alignedl plurality of f rigid sections hinged'togetherv4 for movements on axes extending transversely of thestructure, an 'clon'- gated trussY member generally parallelY to the main member and comprising a longitudinallyaligned Lplurality of rigidsections, adjacent truss member sections being connected by joints permitting limited swivellingand' universal swinging movements therebetween, saidtruss member sections'being connected to--adjacent main member sections by joints permitting limitedv pivotal movements onaxes extending `longitudinally and transversely of" the structure, the centers of universal Vswinging Amovements of the joints between adjacent truss memberA sections being' locatedl in and'movable inlplanes extending transversely of the-structureand including the axesof joints between adjacent main member sections, the said joints between the'truss member'sections and main member sections allowing swinging movements ofithe trussmember sections from operative-truss-formingpositionsto inoperative collapsin'gl positions .wherein-'the' centers of universalmovements between` truss members'ections are aligned with hinge' axes of main member sectionswhereby longitudinally-spaced truss sections maybe placed'respectively-intheir operative andVV inoperative positions with the centers of universal swinging` movements` of'. the" intermediate sections d'en-ing points -1 in a' compound curve'that'is tangent' at one end toa line drawn 12 betweenn centers. of universal swinging movements ofthe jointsbetweenA a connected plurality of" operatively-positioned truss sections and .is tangent at its'other end to a line `drawn between the-centers of universal swinging movements of the joints between' a connected plurality of inoperatively-positioned truss sections, and latch mechanism independently and releasably locking thelside sections in their operative positions.

3. In an elongatedl structure of the class described, an elongated main member comprising aV longitudinally-aligned plurality of rigid sections hinged together for movements on axes eX- tending transversely of-the'structure, a laterallyspaced plurality of truss members extending generally parallel to the main member and each comprising a longitudinally-aligned plurality of rigid sections, adjacent sections of each truss member being connected by joints permitting limited swiveiling and universal swinging movements therebetween, said truss member sections being connected to adjacent main member scctions by joints permitting limited pivotal movements on axes extending longitudinally and transversely oi thestructurel, the centers of universal swinging movements of the joints between adjacent-truss-member vsections being located in and'movable in planes extending transversely of the structure and' including the axes of joints between adjacent main member sections, the said joints between truss member sections and main member sections alowing swinging movements of the truss member sections from operative truss-forming positions to inoperative collapsing positionswherein the centers of'universal swinging movements between said truss member sections are aligned with hinge axes of main member sections.

4. The structure deihed in claim 3 in further combination with latch mechanism independently and releasably lockingthe truss member sections in their operative positions.

5. In an elongated structure of the class described, an elongated main member comprising a longitudinally-alignedv plurality' of rigid sections-connected by hinge jointson axes extending transversey of`r the structure, an elongated truss member generally parallel to the main member and'comprising a longitudinally-aligned plurality of rigid sections, joints connecting adjacent truss member sections for limited swivellingfand universalmvinging movements one in respect to the other, each truss member section being connected to anadjacent. main member section by a-ccmp'ound pivot joint'having intersecting axesV one of which e-Xtends'longitudinally of the structure and the other of 'which extends substantially perpendicular to the first-mentioned axes of said compound pivot joint', the centers oi universal swinging movements ofthe joints between adjacent truss member sections being located in and movable in planesextending transversely of the structure-andincludingthe axesI of hinge joints between adjacent main'member sections, the said compound pivotjoints between truss member sections and'mainmember sections-allowing swinging movements of the truss member sections on their longitudinal axes from operative trussformingpositions-` to inoperative collapsing positions wherein the-centers'of universal swinging movementsbetween truss member sections are aligned with thehingeaxesl of the main member sections.`

6. Tnestructure defined* in claim 5 in further combinationwith a latch mechanism independ- 13 ently and releasably locking the truss member sections in their operative positions.

I'7. The structure defined in claim 5 in which there is a plurality of sectional truss members arranged in laterally-spaced parallel relation, the sections of all truss members being jointed together and to adjacent main member sections in the manner dened.

8. The structure defined in claim 5 in which there is a plurality of sectional truss `members arranged in laterally-spaced parallel relation, the sections of all truss members being joined together and to adjacent main member sections in the manner defined and in still furthercombination with latch mechanism independently and releasably locking the said truss member sections in their operative truss-acting positions.

9. In a colapsble channel-forming structure, a channel bottom and opposite channel sides, the channel bottom and opposite channel sides each being made up of a plurality of rigid sections, adjacent bottom sections being connected by hinge joints having axes of movement extending transversely of the channel, hinge joints connecting adjacent side member sections for relative movements on axes extending substantially perpen dicular to the longitudinal direction of the elongated structure of the channel, hinge joints connecting each side section to a laterally-adjacent bottom section for movements on axes extending longitudinally of the extended channel, the said axes of movement of the joints between longitudinally-adjacent side member sections being located in and movable in planes extending transversely of the channel and including the axes of hinge joints between adjacent main member sections, the said side member sections being movable from channel side-forming, truss-acting'positions to inoperative collapsing positions wherein the said axes of movement of the joints adjacent channel side sections being connectedv by joints permitting limited swivelling and universal swinging movements therebetween, the channel side sections being connected to adjacent cooperating channel bottom sections by joints permitting limited pivotal movements on axes extending longitudinally and transversely of the channel, the rcenters of universal swinging movements of the joints between adjacent channel side sections being located in and movable in planes extending transversely of the channel structure and including the axes of hinge joints between adjacent bottom sections.

l". 1n a collapsible channel-forming structure, a channel bottom and opposite channel sides, the channel bottom and channel sides being each =made up of a plurality of rigid sections, adjacent channel bottom sections being hinged together von axes extending transversely of the channel,

14 channel side sections being connected to adjacent cooperating channel bottom sections by joints permitting limited pivotal movements on axes extending longitudinally andtransversey of the channel, the centers of universal swinging movements of the joints between adjacent channel side sections being located in and movable in planes extending transversely ci the channel structure land including the axes of hinge' joints between adjacent bottom sections, the said joints between the side sections and the bottom sections allowing swinging movements of the side sections from operativechannel side-forming truss-acting positions to inoperative channel-collapsing positions wherein the centers of universal swinging movements between the side sections are aligned with the hinge axes between adjacent bottom sections, whereby longitudinally-spaced .sections of each side may be placed respectively in their operative and inoperative positions with the centers of universal swinging movements of vthe intermediate sections dening points in a .plurality of longitudinally-aligned rigid sections hinged together on axes extendingv transversely of the ladder, the hinge axes of laterally-opposite rail sections being aligned, ladder rungs extending between and rigidly connecting laterally-opposite sections of opposite ladder rails, laterallyspaced truss-acting side members extending substantially parallel to opposite ladder rails, said truss-acting side members each being made up oi a plurality of longitudinally-aligned rigid sections connected by joints permitting relative swinging movements on axes extending transversely of the ladder, the side member sections being connected to laterally-adjacent ladder rails byv joints permitting relative pivotal movements on axes extending longitudinally of the ladder, the side member sections being movable with respect to the ladder rails from operative truss-acting positions to inoperative collapsing positions wherein the axes of the joints between the side member sections are aligned with the axes between ladder rail sections, vand latch mechanism releasably locking said side sections in their operative posi-- tions. 14, In an extension ladder structure, laterallyspaced parallel ladder rails each made lup of a plurality of longitudinally-aligned rigid sections hinged together onaxes extending transversely of the ladder, the hinge axes of laterally-opposite i rail sections being aligned, ladder rungs extendingbetween and rigidlyconnecting laterally-opposite sections ofopposite ladder rails, laterally-spaced i truss-acting side members extending substantially parallel to opposite ladder rails, said truss-acting side members each being made of a plurality ci longitudinally-aligned rigid sections connected by joints permitting limited swivelling and universal swinging movements therebetween, joints connecting the side member sections to laterally-adjacent ladder rails for compound pivotal movements on axes extending longitudinally and transversely ofthe; ladden. the. centers of `universal swinging movements of. the side member joints being locatedin-andmovable in planesextending tra-ns`1 versely of theiadder,andy including the .axes ci adjacentcladder. rail section joints, the said trussacting,sidermembersections being movable with respect. tothe.;ladderY rails from operative trussacting-,positions-to inoperative collapsing positions wherein theY centers of universal swinging movements between side member sections are aligned with theaxes of laterally-adjacent ladder 15. In an extension: ladder structure; laterally spaced parallel ladder rails each made up ofa plurality o longitudinally-aligned rigid sections hingedtogether on axes extending transversely of the'ladder,` theA hinge axes of laterally-opposite rail sections being aligned, ladder rungs extendingbetvfeen and rigidly connecting laterally-opposite-sections of opposite ladder rails, laterally# spacedl truss-acting side members extending substantially parallel' to opposite ladder raiis,` said truss-acting.sidemembers each being made up of a plurality of longitudinally-alignedrigid Vsections connected* by joints permitting limited' v ivelling and universal swinging movements therebetween, joints` connecting; the; side member sections to laterally-adjacent ladder rails for compound pivotalimovements' on axes extending longitudinally and/.transversely of the latter,v the-centersfoi. uni versal l swinging movements of the side member joints being located in and movable izrplauesextending transversely oil the f ladder and including theaxes of adjacent ladder rail section. joints, the

said .truss-acting'side member sections :being'movable withrespect tothe ladder rails fromv operative truss-acting positions to inoperative collapsing positions wherein the centers of 'universal swinging movements betweenside member: sectionsare aligned with the axesoi laterally-adjacent ladder rails, whereby longitudinally-spaced truss-acting side sectionsxmay be placed" respec- V tively in their operative-and inoperativepositions with the intermediate sections so--po'sitioned'that the centers ofuniversal swinging movements therebetween will denne points on. a compound curve tangent at one end toa line drawn between the centers of universal swinging movement of a plurality of operatively-positioned side sections and tangent at its other end to aline-drawn between a plurality of Vinopcrativelypositioned side sections, and latch mechanism:independently-and releasably lockingathe side sections initheir'operative positions.

16. The structure defined in claim 1 in further combination with cam-acting guidemeans progressively acting uponr theV elongated structure under longitudinal movements thereof in onerdirectionto progressively swing the truss member sections toward their inoperative positions and acting upon the elongated structure under movements thereof in the other direction .to progressivelyswing the truss member sections toward their inoperative positions.

17. The structure dined in claim lf in further combination With a supporting structure of very materially less length than the elongated sectional structure and over which the sectional main member is longitudinally movable, and carnacting guide means carried by theY supporting structure and acting upon the sectional truss member under longitudinal movementsofthe elongated sectional structure in one direction to progressivelyv swing theA truss member: sections toward. their inoperativepositions: and. acting 116 upon the truss member sections undermovements of the elongatedisectional structure'in theother direction to progressively swing the truss member sections toward their operative positional` 18. The structure defined inclaim 1 in further combination With a supportingstructure of very n'iateriallyI less length than the elongated sectional structure and over which the sectional main member is longitudinally movable, and earn-acting` guide means carried by the support ing structure and acting upon the sectional truss member underlongitudinal movements oi the elongated sectional structure in one directionfto progressively swing, the truss member sections toward their inoperative positionsV and acting upon thetruss'member sections under movements of the elongated sectional structure in the other direction to progressively swing the truss member sections toward their operative positions, said cam-acting guide means involving channel forming elements between which portions of the truss' member sections pass under longitudinal movements of' the, elongated structure, said channel-forming elements dening points in a compound curve thatis tangent at one end to a plane intersecting; the centers of' universal swinging movements ci the'joints'between a plurality of operatively-positioned truss member sections and is tangent4 at its other end toa plane intersecting the'centersl of universal. swinging movements of the joints between. a plurality of inoperatively positioned truss member sections;v

19. Thestructuredened in claim 1 in further combination with main member supporting'and guidingstrueture over which the sections oi the main memberare. progressively movable, means for longitudinally advancing and retracting jointed elongated structure, and guidewayforming'means laterally between whichthe portions of: the truss member sections pass under longitudinal movements of the elongated structure. during passage of the jointed elongated structure over the supporting structure, said guideway-forming means involving guideway portions spaced apart a distance equal to the length of a plurality of truss membersections, one of said guideway portions being operatively positioned to vreceive therein operatively-positioned truss member sections and the other thereof being positioned to receive therein inoperativelypositioned truss member sections.

20. The structure'dened in claim 1 in further combination with main member supporting and guiding structure over which the sections oi the main1 member' are progressivelymovable, means for longitudinally advancing and retracting jointed elongated structure, and guideWav-forming means laterally between which the portions of theftruss member sectionspass under longitudinal movements of the elongated structure dur'- ing passage ot the jointed elongated structure over the supporting structure, said guideway= forming means involving guideway portions spaced apart a distance equal to the length of a plurality of truss memberv sections.,v one of said guideway portions being operatively positioned to receive Vtherein'Y operatively-positioned truss member sections and the otherthereof'being positioned toreceive therein inoperatively-positioned truss member sections, said' guideway-forming means alsov involving spaced guideway portions intermediate the first-said guideway portions and so'orientatedthat'thecenters'oftheseveral guide'- way portions: will form', points? in a compound curve: that isttangentr at crie-.end to' a line drawn 19 placed respectively in their operative and inoperative positions with the intermediate sections so positioned that the centers of universal swinging' movements therebetween will define points on a compound curve tangent at oneA end to a line drawn between the centers of universal swinging movement of a plurality of operatively-positioned side sections and tangent at its other end to a line drawn between a plurality of inoperatively-positioned side sections, latch mechanism independently and releasably locking the side member sections in their operative positions, meansfor advancing and retracting the jointed elongated structure with respect to the cam-acting guide means, and a reel on which the elongated structure is wound when the truss member sections are in their inoperative collapsing positions.

26. The structure defined in claim 3 in further combination with means progressively moving the truss member sections toward inoperative positions under retracting movements of the structure in respect thereto and progressively moving the truss member sections toward their operative positions under extended movements of the structure in respect thereto, said means comprising cam-acting guides for each truss member.

27. The structure dened in claim 3 in further combination with a supporting structure of materially-less length than the jointed elongated structure and over which the sectional main member of the elongated structure is longitudinally movable, and cam-acting guide means carried by the supporting structure and acting upon the sectional truss members of the elongated structure under longitudinal movements thereof in one direction to progressively swing the truss member sections toward their inoperative positions and acting upon the sectional truss members under movements of the elongated structure in the other direction to progressively swing the truss member sections toward their operative positions.

28. The structure defined in claim 3 in further combination with a supporting structure of materially-less length than the jointed elongated structure and over which the sectional main member of the elongated structure is longitudinally movable, and cam-acting guide means carried by the supporting structure and acting upon the sectional truss members of the elongated structure under longitudinal movements thereof in one direction to progressively swing the truss member sections toward their inoperative positions and acting upon the sectional truss members under movements of the elongated structure in the other direction to progressively swing the truss member sections toward their operative positions, said cam-acting guide means involving channel-forming elements between which portions of the sections of each truss member pass under longitudinal movements of the elongated structure, the transverse centers of channelorming elements for each truss member defining points in a compound curve that is tangent at one end to a plane intersecting the centers of universal swinging movements of a plurality of loperativelypositioned sections of its truss memnally-aligned plurality of rigid sections connected by universal joints, said universal joints each comprising the biiurcated member carried by one section, a rcooperating tongue member carried by the adjacent section and working in the said bifurcated member, a pivot pin extending between spaced portions of the bifurcated member and having its axes extending substantially perpendicular to the longitudinal direction of the eX- tended Structure, a spherical ring concentrically mounted on said pin within said bifurcated member and seated in a mating spherical socket in the said tongue membere said spherical ring and tongue member being free for unitary limited axial sliding movements on said pin within said bifurcated member; compound pivot joints connecting the truss member sections to adjacent main member sections, said compound pivot joints each comprising a body pivotally mounted on adjacent main member section on an axis extending generally parallel to the longitudinal direction of that section and the extended structure, a shank rigid with Vthe adjacent truss member section and mounted in said pivoted body for pivotal and limited axial sliding movements in said pivoted body on an axis extending generally perpendicular to the axis of the said pivoted body and parallel to the axes o the said pivot pin of the universal joints between adjacent sections; and latch mechanism independently and releasably locking the truss member Sections in operative positons, said latch mechanism each comprising a universal joint shank, a latch detent carried by and projecting from a projected end portieri of said universal joint shank, an element carried by the adjacent main member section and having a generally-segmental surface about which said latch detent is adapted to travel under lateral swinging movements of the adjacent truss member section and having a notch adapted to receive the latch detent under outward sliding movements of the shank in the pivoted body, and yielding means biasing the shank to move outy warclly toward latch-locking position.

KARL O. LARSON.

REFERENCES CITED UNITED STATES PATENTS Name Date Le Roy Jan. 17, 1939 Number 

